Valve packing for metallurgical shaft furnaces

ABSTRACT

A valve construction particularly for closing the connection of a charging hopper to the furnace throat of a blast furnace comprises a valve seat for the hopper which is arranged in a recess portion or out of the stream of the material to be poured therefrom into the furnace. A valve closure member includes an inner portion having a cross section which makes it more flexible than an outer thicker portion. The outer sealing rim is formed in the thickened outer portion and it is rounded. The valve seat defined at the lower end of the charging hopper advantageously includes an annular groove which is connected to a source of gas under pressure and the groove is located over the rounded sealing rim of the valve member. Gas under pressure is directed to and through the groove and blows against the sealing rim of the valve member to provide the double function of preventing escape of gases from the furnace and cleaning the seat of the valve member for proper sealing purposes.

' United States Patent Nieboer [54] VALVE PACKING FOR METALLURGICAL SHAFT FURNACES [72] inventor: Pieter Hendrik Nieboer, Kapellen, Germany [73] Assignee: Demag Alrtiengesellsehait, Duisburg, Germany [22] Filed: June 11, 1970 211 Appl. No.2 45,311

[30] Foreign Application Priority Data ,Oct. 1, 1969 Germany ..P 19 49 471.4

[52] US. Cl. ..266/27, 214/18 V [51] Int. Cl ..F27b 1/20 [58] Field ofSearch ..266/27, 31; 2l4/18R, 18 V,

[56] References Cited UNITED STATES PATENTS 3,182,983 5/1965 Tsujihata et al. ..266/27 2,765,935 10/1956 Schuman....; ..214/36 [451 July 25, 1972 1,868,924 7/1932 Spicknall ..214/36 1,742,733 1/1930 Stoecker ..266/31 Primary Examiner-Gerald A. Dost Attorney-McGlew and Toren ABSTRACT A valve construction particularly for closing the connection of a charging hopper to the furnace throat of a blast furnace comprises a valve seat for the hopper which is arranged in a recess portion or out of the stream of the material to be poured therefrom into the furnace. A valve closure member includes an inner portion having a cross section which makes it more flexible than an outer thicker portion. The outer sealing rim is formed in the thickened outer portion and it is rounded. The valve seat defined at the lower end of the charging hopper advantageously includes an annular groove which is connected to a source of gas under pressure and the groove is located over the rounded sealing rim of the valve member. Gas under pressure is directed to and through the groove and blows against the sealing rim of the valve member to provide the double function of preventing escape of gases from the furnace and cleaning the seat of the valve member for proper sealing purposes.

8 Claims, 3 Drawing Figures VALVE PACKING FOR METALLURGICAL SHAFT FURNACES SUMMARY OF THE INVENTION This invention relates in general, to the construction of metallurgical furnaces, and in particular, to a new and useful valve construction for shaft furnaces, particularly for blast furnaces which are operable at high pressures, and'wherein the valve member provides a pressure lock at the furnace throat at the location of a sealing surface or valve seat located outside of the stream of the charged material.

It is known practice especially for storage bunkers arranged above the throat of a blast furnace to provide hinged covers which are designed as sealing valves which are pivotally mounted in the top of the furnace at a location in which they can be pivoted to an opened position outside of the path of the charging material which moves downwardly through the hopper and through the valve opening. Such sealing valves have the advantage of having a smaller diameter then the socalled distributor bells which are also employed for achieving a similar sealing effect at the charging hopper discharge. A disadvantage inthe use of the charging bells is that they do not withstand high pressure operation and when such high pressure operation is carried out it is usual to employ pivotal closing valve members. Difficulties in operation arise due to the high temperatures and also especially in blast furnaces due to flue dust which cause wearing of all of the valve seal seats. The impingement of dust particles, however, is not the only cause of defects of the known valve constructions. A special obstacle resides in dust deposition because relatively large depressions must always be expected at the seal seats after repeated closing and openings cycles of operations. For this reason, a valve sealing surface having a ring profile with a counter profile in the manner of, a nut and screw is particularly undesirable. A depression formed in a valve surface would provide a location for the accummulation of flue dust so that after a while a seal valve could no longer execute the full closing movement and the accumulation of dust will undoubtedly be uneven so that the closing will not be uniform. The known valve constructions have the disadvantage that they do not satisfactorily solve the problem of dust accumulation or the stressing of the valve members and parts by temperature loadmg.

Gas seals have been employed for various valve sealing arrangements. However, in most cases any dust particles present in the discharge gas are not taken into consideration but only the temperatures as in the case for example with combustion engines. In most branches of technology therefore the problem of gas seals is solved for gases without any particular entrainment of dust. It is necessary to take into consideration also the kind of flue dust in which are contained particles of metallic and ceramic origin and cause especially heavy wear.

In accordance with the present invention, there is provided a valve construction which includes sealing parts having a high efficiency, despite higher temperature and dust entrainment in the environment employed and despite certain properties of flue gas dust in metallurgical operations which take place at high velocities and high pressures. The valve seat of the valve is advantageously located at the connection of the hopper to the furnace throat and located in a recessed area out of the stream of flow of the material. A valve member which is adapted to be pivotally mounted adjacent one side of the discharge of the hopper includes a central or inner portion having a cross section which makes it more flexible than an outer wider portion at the periphery. A sealing rim or sealing edge is defined at the upper part of the outer portion which is rounded. The elasticity of the inner portion of the valve member causes an adaptation of the sealing edge to the sealing surface even if, at higher temperatures, a deformation of the valve should occur. Also an elevated internal pressure, which is precisely what the seal is employed for delimiting, can be utilized inasmuch as with an increase of internal pressure the elasticity of the valve permits a higher sealing force. If, in fact,

the gas pressure in the interior of the furnace zone of a blast furnace increase, then the valve member is subject to a socalled membrane effect which causes the sealing ring to migrate outwardly by a small amount. The abrading effect connected therewith permits, surprisingly, the pushing aside of any dust of any dirt present on the sealing surfaces so that there is a self-cleaning effect. Both sealing surfaces therefore obtain a mutually optimum bearing content which permits excellent sealing even with high pressure conditions. The rounding of the outer portion or rim of the valve member contributes to the construction of a sealing rim of desirable width in every bending position of the membrane construction of the valve member.

In a form of the invention, the valve member advantageously includes an annular sealing rim of oval shape which is planar and ground (polished). The sealing rim of the sealing valve therefore rolls off on the ground surface during periods of different internal gas pressure admission, that is during pressure build-up. A smooth surface facilitates removing the dirt and further facilitates the sliding, or rolling off, of the corresponding parts of the circumference line of the valve cross section.

in accordance with another feature of the invention the sealing surface, or groove of the valve seat, is provided with an encircling groove in the oval zone of the sealing rim of the valve member. The groove is centered in respect to the actual seating area, and it provides a means for admitting a gas under pressure at such location in order to prevent dust accumulation. In addition, the rim of the valve member can take support on two points at the oval circumference of the valve seat and it is therefore possible to attain a particularly good sealing effect in the pressure build up. The elasticity of the sealing valve member contributes to the straightening of warped sealing valves and the adapting of them to the form of the groove edges of the valve seat. The cross sectional edges of the encircling groove are designed in the form of an oval to provide an exact adaptation of the sealing rim surface of the valve member to the sealing edges of the valve seat. The groove is connected to means for supplying an inert gas under pressure through the groove and over the valve seat and the rim of the valve member forming the closure. In the opened position of the sealing valve, therefore, a relatively-large amount of inert gas depending on the pressure conditions will flow through the groove and over the seat and the rim of the valve member to clean both and also to prevent the escape of dust laden flue gas from the furnace through the hopper. The construction therefore improves the sealing effect of the valve packing in several respects. In accordance with a further feature of the invention it is essential that the parts forming the sealing surfaces be such that they may be exchanged after relatively long periods of use. It is therefore expedient to arrange the portion of the valve seat ring of a plurality of interengageable ring flange elements which may be located on the head of the furnace and form a connection from the furnace to the storage bunkers thereabove. The groove centered in the valve seat may be formed by two rings arranged concentrically and having difierent diametrical dimensions to permit their interengagement. This simplifies the production of such rings and the formation of the groove gap therebetween. Such surfaces can be machined on a lathe or ground on suitable grinding equipment to form the sealing surfaces. The construction makes it possible to replace the rings easily and to keep them in a ready supply for replacement as need be. Any rings which no longer seal may be rapidly exchanged.

A further desirable effect of the inventive construction is in respect to process engineering. It is intended to retain the valve just before it reaches the sealing position to leave it temporarily open in this position and then to accelerate the inert gas stream and only then to transmit the full sealing force to the sealing valve rim. With such a procedure there is caused a surprising effect of self-cleaning. To retain the sealing valve just before it reaches the sealing position, ensures that a narrow flow channel is formed in which the inert gas momentarily undergoes an accelleration and thus exerts a better cleaning action. If therefore, especially before the closing of a sealing valve, the seal-cleaning is carried out; then the sealing seat is, with the greatest certainity,in a desired state immediately the closing of the valve. In the short time between retaining and ,closing a deposition of dust is hardly possible. With a correspondingly high accelleration of the inert gas, which may consist of a nitrogen for example, a correspondingly high cleaning force can be produced. The groove formed in the valve seat brings about a division of the inert gas stream and hence a particularly strong impingement on the dome portion of the sealing rim so that the deflection of the gas stream occurs in two directions to clean the rim of any adhering dust.

Accordingly, it is an object of the invention to provide an improved valve sealing construction for a metallurgical furnace which includes a valve member having a wire rim cross section then a central cross section so as to provide a certain flexibility to the interior portion and which includes a rounded rim engageable with a valve seat which is adapted to be recessed in a position out of these charging material flow.

A further object of the invention is to provide a valve construction which includes a valve member having a thickened widened rounded rim which is closeable against a seat having a'sealing surface with an oval sealing seat interrupted centrally by a groove, and wherein the groove is advantageously connectible to an inert gas under pressure which blows through the groove and the seat to clean the seat and the rim of the valve member during operation.

A furtherobject of the inventionis to provide a method for operating a valve packing wherein the valve is moved so that it was retained just before it reaches the sealingposition and temporarily left in this position, an inert gas is then delivered through an opening in the valve seat and is accelerated while the valve member is in the temporary position and only then is the full sealing force transmitted to the sealing valve member through the rim.

A further object of the invention is to provide a sealing valve construction for a metallurgical furnace which is simple in design, rugged in construction, and economical to manufacture.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a partial transverse section of a valve construction for the connection between a hopper and a furnace head constructed in accordance with the invention;

FIG. 2 is a partial sectional view of another embodiment of the invention; and

FIG. 3 is a view of the apparatus indicated in FIG. 2 shown in a partially opened or partially closed position.

GENERAL DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings in particular the invention embodied in FIG. 1 includes a valve closure assembly for regulating the flow of a charging material from a hopper 1 into the head portion of a blast furnace 5. In accordance with the invention, the valve closure assembly includes a ring flange or attachment member 2 extending between the hopper 1 and the furnace 5, and defining a valve sealing surface or valve seat 4 on an underside of a bottom flange portion 2a of the ring at a location in which the seat 4 is out of the flow path of the material moving through the hopper 1 into the blast furnace head 5. The construction of the invention is used in place of the conventional bell for closing off the charging flow. The valve seat 4 is flat and therefore is made especially smooth by grinding.

In accordance with a feature of the invention, a valve member, or seal valve, generally designated 6, is pivotally mounted at 30 about its one end 6a to permit it to be moved to a closed position indicated in the drawings or pivoted to one side of the flow channel 1a of the hopper in an opened position which permits the equalization of the hopper pressure to the furnace pressure and also the flow of material in some instances. The valve member 6 includes a relatively thin walled inner cross sectional zone or portion 7 and an outer peripheral or marginal portion 8 having a thickened or widened sectional formation. An intermediate wall portion 9 of the valve member is arched similar to a membrane or diaphragm. The outer cross sectional zone 8 has a sealing rim 10 of rounded form defined along its upper edge. The rim 10 is arched in a manner such that there is always formed a relatively wide contact area 11 in the form of an encircling ring around the circumference of the valve member 6 regardless of the annular position which the inner cross section 7 of the sealing valve member 6.

In the embodiment indicated in FIG. 2, a charging hopper 1 includes a ring member connection 2 between it and a furnace head or top portion 5 In this construction a valve seat 4' is formed with an oval shaped receiving seat portion 4a which is intersected by an annular groove 12 which extends completely around the circumference of the seat 4' as shown by dotted line 15. The ring assembly 2' is made of two separate ring parts 13 and 14 which are arranged concentrically together to form the groove 12. The oval groove 40 includes separated curved sections 16 and 17 which correspond together to the general shape of the sealing rim [0 of a valve member 6'. One or more conduits 18 are connected to the groove 12 at the upper or inner end thereof and a gas under pressure, such as an inert gas, is directed in the direction of the arrow 19 through the conduit 18 and into the grooves 12.

The ring assembly 2' can also be formed by ring parts such as the parts 13 and 14, which are designed as inserted elements, that is, they are indpendent of rings which are inserted in the base body of the ring flange assembly 2. Such a construction facilitates the production or the exchange of the ring parts 13 and 14.

In the arrangement of FIG. 3, the method of operation of the valve assembly indicated in FIG. 2 is shown. The inert gas flows under pressure in the direction of the arrows 19 through the channels 18 and into the groove 12 and then impinges on the sealing rim 10 over the highest point 11 thereof. This impingement divides the gas flow into two narrow flow cross sections of high flow velocity. By the momentary conversion of the flows into pressure energy any dust adherring on the sealing rim is blown away. At the same time, there forms a corresponding pressure in the spaces 22 and 23. The counter pressure of the inert gas consequently contributes to the mainteneance of the pressure difference between the hopper and the top of the furnace 5" and, in addition, the gas flow aids in preventing the escape of gases from the furnace zone 22.

The valve member 6' is retained just below the exit to the groove 12 temporarily when it is moved to closing engagement with the valve seat 4'. While it is temporarily left in this position, the inert gas stream is accelerated and thereafter the full sealing energy force is transmitted to the sealing valve rim.

I claim:

1. A valve construction for a furnace such as a pressure operated blast furnace for location between a discharge opening of a charging hopper and said furnace,.comprising ring means adapted to be positioned around said discharge opening and having an undersurface defining an annular substantially horizontal valve seat surrounding and offset laterally from the discharge opening and the flow path of the charging material, and a valve member movable toward and away from said valve seat, said valve member comprising a flexible diaphragm having outer and inner portions of different crosssection, the inner portion having cross-section such that it is more flexible than said outer portion, said outer portion extending around the periphery of said valve and defining a rounded sealing rim having a top portion engageable with said valve seat.

2. A valve construction, according to claim 1, wherein said valve seat defines an oval recessed portion for sealing with said valve member, said valve member outer portion being oval.

3. A valve construction, according to claim 1, wherein said ring means undersurface defines said valve seat, a groove extending inwardly from said undersurface and defining an annular encircling groove having an entrance mouth forming a sealing recess for said rim portion of said valve member.

4. A valve construction, according to claim 3, wherein said valve seat includes a curved portion on each side of the entrance to said groove for receiving said sealing rim of said valve member.

5. A valve construction, according to claim 4, including means for directing an inert gas into said groove said ring means comprising at least exchangeable ring member.

6. A valve construction, according to claim I, wherein said ring means includes first and second ring members said ring members, together defining an annular groove having a mouth portion forming said valve seat at least one of said ring members being exchangeable.

7. A valve construction according to claim 1, including pivot means located to one side of said discharge opening for pivotally mounting said valve member.

8. A method of operating a pressure seal valve between a hopper and a furnace head using a valve member having a sealing rim portion engageable in a recess sealing seat of a ring member located between the hopper and the furnace, comprising moving the valve member in a closing direction toward said valve seat, stopping the movement of said valve just prior to engagement with said valve seat and directing an inert-gas from said valve seat across the surface of said sealing rim to affect the cleaning of the valve seat and the sealing rim, and thereafter applying a full sealing force of the valve member to tightly seal said valve rim with said valve seat. 

1. A valve construction for a furnace such as a pressure operated blast furnace for location between a discharge opening of a charging hopper and said furnace, comprising ring means adapted to be positioned around said discharge opening and having an undersurface defining an annular substantially horizontal valve seat surrounding and offset laterally from the discharge opening and the flow path of the charging material, and a valve member movable toward and away from said valve seat, said valve member comprising a flexible diaphragm having outer and inner portions of different cross-section, the inner portion having cross-section such that it is more flexible than said outer portion, said outer portion extending around the periphery of said valve and defining a rounded sealing rim having a top portion engageable with said valve seat.
 2. A valve construction, according to claim 1, wherein said valve seat defines an oval recessed portion for sealing with said valve member, said valve member outer portion being oval.
 3. A valve construction, according to claim 1, wherein said ring means undersurface defines said valve seat, a groove extending inwardly from said undersurface and defining an annular encircling groove having an entrance mouth forming a sealing recess for said rim portion of said valve member.
 4. A valve construction, according to claim 3, wherein said valve seat includes a curved portion on each side of the entrance to said groove for receiving said sealing rim of said valve member.
 5. A valve construction, according to claim 4, including means for directing an inert gas into said groove said ring means comprising at least exchangeable ring member.
 6. A valve construction, according to claim 1, wherein said ring means includes first and second ring members said ring members, together defining an annular groove having a mouth portion forming said valve seat at least one of said ring members being exchangeable.
 7. A valve construction according to claim 1, including pivot means located to one side of said discharge opening for pivotally mounting said valve member.
 8. A method of operating a pressure seal valve between a hopper and a furnace head using a valve member having a sealing rim portion engageable in a recess sealing seat of a ring member located between the hopper and the furnace, comprising moving the valve member in a closing direction toward said valve seat, stopping the movement of said valve just prior to engagement with said valve seat and directing an inert gas from said valve seat across the surface of said sealing rim to affect the cleaning of the valve seat and the sealing rim, and thereafter applying a full sealing force of the valve member to tightly seal said valve rim with said valve seat. 